Find prt:qsu, given that p:r=2:3, q:s=4:3, r:t=8:9, s:u=3:2 and t:q=3:4

In 40 litres of a mixture the ratio of milk to water is 7:1. In order to make the ratio of milk to water as 3:1, the quantity of water that should be added to the mixture will be

The speeds of Aniket, Brihat and Chatur are in the ratio of 4:3:2. If Chatur takes half an hour more than Brihat to travel from P to Q, what is the total time taken by Aniket to travel from P to Q and then back from Q to P?